1. Field of the Invention
The present invention relates to a novel dye for use in a photoelectronic device, wherein the photoelectronic device is comprised of a photoanode comprising the dye. More specifically, the present invention relates to a novel dye for use in a photoelectronic device in which the dye is derived through the introduction of a group that narrows the dihedral angle of the dye ligand as well as the introduction of conjugated groups. The resulting novel dye has increased light sensitivity and absorption efficiency.
2. Description of the Related Art
In recent years, numerous studies have focused on various alternative energy sources for conventional fossil fuels in an attempt to solve energy consumption problems. In particular, extensive research into the effective utilization of natural energy resources, including wind power, atomic energy and solar energy, have been conducted in an effort to identify alternative resources capable of replacing petroleum resources that may be used up within the next several decades.
Unlike other energy sources, solar cells utilize inexhaustible solar energy, and are environmentally friendly. Since the development of the first selenium (Se) solar cell in 1983, solar cells have elicited a great deal of attention and interest.
Many materials have been proposed as candidates for solar cells. Silicon is currently used in most commercially available solar cells. However, since silicon solar cells are expensive to manufacture, there are some limitations in regards to the practical application of the cells and the improvement in the efficiency of the cells. In an effort to overcome these limitations, the development of dye-sensitized solar cells that can be fabricated at reduced costs is currently ongoing.
Unlike silicon solar cells, dye-sensitized solar cells are photoelectrochemical solar cells that are comprised of photosensitive dye molecules capable of absorbing visible wavelengths to form electron-hole pairs, and a transition metal oxide for transferring the generated electrons. Various dye-sensitized solar cells have hitherto been developed. Of these, a representative dye-sensitized solar cell was reported by Grätzel et al. in Switzerland in 1991 (Nature, 1991, vol. 353, pp 737-740). The solar cell developed by Grätzel et al. comprises a photoanode comprising titanium dioxide nanoparticles covered with dye molecules, a platinum electrode as a cathode, and an electrolyte filler between the electrodes. Since this solar cell can be fabricated at a low cost relative to the electric power generated, it has received a great deal of attention as a potential replacement for conventional solar cells.
The structure of a conventional dye-sensitized solar cell is shown in FIG. 1. Referring to FIG. 1, the dye-sensitized solar cell comprises a photoanode 107, comprising a transparent electrode 101 and a light-absorbing layer 104, an electrolyte 102, and a cathode 103, wherein the light-absorbing layer is generally comprised of a metal oxide 105 and a dye 106.
The dye 106 may be in a neutral state (S), a transition state (S*), or an ionic state (S+). When sunlight is incident on the dye, the dye molecules undergo an electronic transition from the ground state (S/S+) to the excited state (S*/S+) resulting in the formation of electron-hole pairs. The electrons in an excited state are injected into a conduction band (CB) of the metal oxide 105 resulting in the generation of an electromotive force.
As such, the performance of dye-sensitized solar cells is largely dependent on the light sensitivity and absorption efficiency of the dye(s). Thus, continuous efforts have been made in the field of dye-sensitized solar cells to develop a new dye that exhibits improved absorption properties and increased absorption efficiency for sunlight. For example, Narukuni Hirata et al. have reported the N845 Dye whose structure is chemically modified by the addition of a secondary electron donor moiety, N,N-(di-p-anisylamino)phenoxymethyl (Chem. Eur. J., 2004, Vol. 10, pp. 595-602). However, there is still an unmet need in the art to develop a dye that exhibits improved absorption properties.